package com.funindata.ocr.baidu.Utils;
/**
 *
 * @Author zhengyingjun
 * @Description ：base64工具类
 * @Date 2019/2/25
 **/

public class Base64Util {
        private static final char last2byte = (char) Integer.parseInt("00000011", 2);
        private static final char last4byte = (char) Integer.parseInt("00001111", 2);
        private static final char last6byte = (char) Integer.parseInt("00111111", 2);
        private static final char lead6byte = (char) Integer.parseInt("11111100", 2);
        private static final char lead4byte = (char) Integer.parseInt("11110000", 2);
        private static final char lead2byte = (char) Integer.parseInt("11000000", 2);
        private static final char[] encodeTable = new char[]{'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};

        public Base64Util() {
        }

        public static String encode(byte[] from) {
            StringBuilder to = new StringBuilder((int) ((double) from.length * 1.34D) + 3);
            int num = 0;
            char currentByte = 0;

            int i;
            for (i = 0; i < from.length; ++i) {
                for (num %= 8; num < 8; num += 6) {
                    switch (num) {
                        case 0:
                            currentByte = (char) (from[i] & lead6byte);
                            currentByte = (char) (currentByte >>> 2);
                        case 1:
                        case 3:
                        case 5:
                        default:
                            break;
                        case 2:
                            currentByte = (char) (from[i] & last6byte);
                            break;
                        case 4:
                            currentByte = (char) (from[i] & last4byte);
                            currentByte = (char) (currentByte << 2);
                            if (i + 1 < from.length) {
                                currentByte = (char) (currentByte | (from[i + 1] & lead2byte) >>> 6);
                            }
                            break;
                        case 6:
                            currentByte = (char) (from[i] & last2byte);
                            currentByte = (char) (currentByte << 4);
                            if (i + 1 < from.length) {
                                currentByte = (char) (currentByte | (from[i + 1] & lead4byte) >>> 4);
                            }
                    }

                    to.append(encodeTable[currentByte]);
                }
            }

            if (to.length() % 4 != 0) {
                for (i = 4 - to.length() % 4; i > 0; --i) {
                    to.append("=");
                }
            }

            return to.toString();
        }

}
